Fingerprint matching systems that detect fingerprints and compare them with fingerprint data in a stored database have been available in the prior art for some time now. Such fingerprint identification systems are being increasingly used in various devices for identifying users. For example, door locks can be operated through the matching of fingerprints instead of ID numbers. This prevents breach of security through misuse of ID numbers by unauthorized persons. Locks that use fingerprint matching systems are currently in use.
Conventional fingerprint matching systems found in the prior art, however, have some shortcomings. In conventional systems, identification is performed by first sensing the fingerprint data and comparing it with fingerprint data in a database. So, such systems require a sensor (hereinafter referred to as “fingerprint sensor”) that detects fingerprint data which can then be used for matching. In conventional systems, fingerprint sensors are used which detect the fingerprint data utilizing the principles of light or electrostatic capacitance.
However, the optical fingerprint sensors sometimes cannot accurately detect fingerprint data in strong ambient light, such as when used outdoors during the day. Also, capacitance-based sensors at times have to cope with noise because of electromagnetic waves present in the environment where they are used. Moreover, both types of prior art fingerprint sensors are prone to error in the presence of moisture. Therefore, when such sensors are used outdoors on a wet day or in locations with high humidity, accurate fingerprint data sometimes cannot be obtained. Still another limitation is that sweat, grease, etc. on the finger often affects the detection accuracy of fingerprint data.
Thus, fingerprint sensors based on light or capacitance have inherent limitations, depending on the environment in which they are used, i.e., the season, geographical location, the weather, etc. This type of lowered detection accuracy of fingerprint data directly leads to the non-functioning of locks that use such fingerprint sensors, considerably limiting the possible applications for such locks. Another problem with optical fingerprint sensors is that a fairly large-sized device is required for accurate detection of fingerprint data. So, optical fingerprint sensors cannot be conveniently used for as part of a lock for objects that are relatively small.
The present applicant had earlier applied for and was granted a Japanese Patent (Patent application NO HEI 5-277619/1993 and U.S. Pat. No. 2,557,795) for a pressure-based fingerprint sensor (surface pressure input panel) which did not depend on optical or capacitance input.
The present invention was made in view of the above-described prior art. Its objective is to overcome the shortcomings of conventional fingerprint sensors and to provide locks and switches that use pressure-based fingerprint sensors which are more reliable than conventional sensors.